Single radio wimax interworking

ABSTRACT

In some embodiments a method comprises establishing a layer 2 tunnel between a mobile station coupled to a E-UTRAN and a WiMAX base station, implementing a first signaling interface through the layer 2 tunnel between a mobility management entity (MME) and the WiMAX base station, and preregistering the mobile station with the WiMAX access service network gateway at least in part via the layer 2 tunnel. Other embodiments may be described.

RELATED APPLICATIONS

This application claims the right of priority under 35 U.S.C. §119(e) from U.S. provisional patent application No. 61/275,266, filed Aug. 24, 2009, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Mobile services providers may operate multiple heterogeneous access technologies and networks. Worldwide Interoperability for Microwave Access (WiMAX) is a wireless communication access technology intended to be deployed in accordance with the Institute of Electrical and Electronics Engineers (IEEE) standard referred to as IEEE 802.16. WiMAX networks provide broadband wireless communication over distances which are relatively long. Initial WiMAX deployment may cover only limited areas of service that may already be serviced by the third generation (3G) type cellular networks, such as promulgated by the 3rd Generation Partnership Project (3GPP). Thus, at least during initial deployment of WiMAX networks, islands of WiMAX coverage areas may exist within cellular 3G coverage areas. Hence, it may be useful for a 3G network service provider that deploys WiMAX services to converge WiMAX access and 3G access with seamless vertical mobility, or interaccess. Furthermore, dual mode devices that are capable of communicating with both 3G networks and WiMAX networks are expected to be deployed.

Current solutions for network interaccess in 3GPP standards and the cellular industry utilize Layer 3 (L3) protocols (i.e., client-based Mobile IP) for providing mobility between access technologies. However, such L3 protocol-based methods require simultaneous radio operation of both access technologies to execute a handover operation between a 3GPP network and a WiMAX network. Further, client-based Mobile IP techniques may experience significant latency in performing interaccess handovers that could hinder operation of real-time services such as Voice over Internet Protocol (VoIP) applications or the like.

Protocols have been developed in WiMAX to provide for single-radio handover between a WiMAX network and a 3GPP network. In single-radio handovers various network elements cooperate to manage the handover process between heterogeneous access networks.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanying figures.

FIG. 1 is a schematic illustration of a handover between two or more heterogeneous wireless networks, according to some embodiments.

FIG. 2 is a schematic illustration of a network reference model for single radio interworking of a mobile WiMAX system with a 3GPP access network, according to embodiments.

FIG. 3 is a schematic illustration of an electronic device which may be used to implement one or more network nodes in a wireless network.

FIG. 4 is a flow diagram illustrating operations in a method to preregister a mobile station with a WiMAX network, according to embodiments.

FIG. 5 is a flow diagram illustrating operations in a method to implement a handover from a 3GPP access network to a WiMAX access network, according to some embodiments.

FIG. 6 is a flow diagram illustrating operations in a method to implement a handover from a WiMAX access network to a 3GPP access network, according to some embodiments.

FIG. 7 is a schematic illustration of a state machine for a dual mode 3GPP LTE and WiMAX mobile station, according to embodiments.

FIG. 8 is a schematic illustration of a data structure which may be used to convey capability information, according to embodiments.

FIG. 9 is a schematic illustration of a broadcast data structure, according to embodiments.

FIG. 10 is a flow diagram illustrating operations in an RRC procedure, according to embodiments.

DETAILED DESCRIPTION

Described herein are exemplary methods and network nodes which provides for single radio handover between heterogeneous networks, e.g., between a 3GPP access network and a WiMAX access network. In the following description, numerous specific details are set forth to provide a thorough understanding of various embodiments. However, it will be understood by those skilled in the art that the various embodiments may be practiced without the specific details. In other instances, well-known methods, procedures, components, and circuits have not been illustrated or described in detail so as not to obscure the particular embodiments.

In the following description and/or claims, the terms coupled and/or connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical and/or electrical contact with each other. Coupled may mean that two or more elements are in direct physical and/or electrical contact. However, coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate and/or interact with each other. For example, “coupled” may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements. Finally, the terms “on,” “overlying,” and “over” may be used in the following description and claims. “On,” “overlying,” and “over” may be used to indicate that two or more elements are in direct physical contact with each other. However, “over” may also mean that two or more elements are not in direct contact with each other. For example, “over” may mean that one element is above another element but not contact each other and may have another element or elements in between the two elements. Furthermore, the term “and/or” may mean “and”, it may mean “or”, it may mean “exclusive-or”, it may mean “one”, it may mean “some, but not all”, it may mean “neither”, and/or it may mean “both”, although the scope of claimed subject matter is not limited in this respect. In the following description and/or claims, the terms “comprise” and “include,” along with their derivatives, may be used and are intended as synonyms for each other.

Referring now to FIG. 1, a block diagram of a wireless network illustrating a handover between two or more heterogeneous wireless networks in accordance with one or more embodiments will be discussed. As shown in FIG. 1, wireless network 100 may comprise a WiMAX access network coverage area 112 disposed in and/or proximate to a 3GPP access network coverage area 114. WiMAX access network coverage area 112 may be serviced by a WiMAX Base Station (WiMAX BS) 116, and likewise 3GPP access network coverage area 114 may be serviced by a 3GPP access E-UTRAN 118, e.g., a 3GPP access network or a derivative thereof, although the scope of the claimed subject matter is not limited in this respect.

In one or more embodiments, a user equipment/mobile station (UE/MS) 110 may move between WiMAX access network coverage area 112 and 3GPP access network coverage area 114. If mobile station 110 moves from WiMAX coverage area 112 to 3GPP access network coverage area 114, or if mobile station 110 movies from 3GPP access network coverage area 114 to WiMAX coverage area 112, a handover operation 120 may occur between the WiMAX access network to the 3GPP access network, or from the 3GPP access network to the WiMAX access network. In one or more embodiments, handover operation 120 may implement a handover method between WiMAX and 3GPP services where the mobile station 110 may have one radio active at any given time. To enable single radio operation that a single radio module of a multi-communication platform is on at any given time, inter-radio access technology (inter-RAT) info exchange may be utilized. Example architectures of wireless networks capable of implementing a handover between access services is discussed with respect to FIG. 2.

Referring now to FIG. 2, a block diagram of an architecture of a wireless network capable of implementing single radio handover between another wireless network in accordance with one or more embodiments will be discussed. In one embodiment, FIG. 2 illustrates components of an architecture for handover between a 3GPP access network and a WiMAX access network. In one or more embodiments, a user equipment and/or mobile station 110 couples to an evolved-UTRAN (E-UTRAN) 210 via an LTE-Uu interface which in turn couples to serving gateway 216 via an S1-U interface. Serving gateway 216 couples to packet data network gateway (PDN Gateway) 222 via an S5 interface, which is in turn coupled with Internet Protocol Services (IP Services) server 226 to allow user equipment and/or mobile station 110 to connect to the internet, although the scope of the claimed subject matter is not limited in this respect.

E-UTRAN 210 couples to a mobility management entity (MME) 212 via an S1-MME interface, and the serving gateway 216 couples to the MME via an S11 interface. In some embodiments a WiMAX Interworking Function (IWF) 214 is added to MME 212. IWF 214 implements logic to manage interworking between a WiMAX network and a 3GPP network, e.g., a 3GPP network. MME 212 couples to a Home Subscriber Server (HSS) 220 via an S6a interface, which in turn coupes to an Authentication, Authorization & Accounting (AAA) server 230.

In some embodiments WiMAX base station 116 may couple to MME 212 via an S101 interface and to WiMAX ASN-GW 218 via an R6 interface. The WiMAX ASN-GW 218 may couple to the serving gateway 216 via an S103 interface. Similarly, the WiMAX ASN-GW 218 may couple to the PDN-GW 222 via an S2a interface. The WiMAX ASN-GW 218 may couple to the PCRF 224 and the AAA server 230.

FIG. 3 is a schematic illustration of an electronic device 300 which may be used to implement one or more network nodes in a wireless network. By way of example, and not limitation, electronic device 300 may be used to implement the MME 212 and/or the WiMAX ASN-GW 218. In one embodiment, electronic device 300 may be implemented as a computer-based system that may be coupled to one or more networks.

Referring to FIG. 3, system 300 includes system hardware 320 and memory 330, which may be implemented as random access memory and/or read-only memory. System hardware 320 may include one or more processors 322, input/output ports 324, network interfaces 326, and bus structures 328. In one embodiment, processor 322 may be embodied as an Intel® Core2 Duo® processor available from Intel Corporation, Santa Clara, Calif., USA. As used herein, the term “processor” means any type of computational element, such as but not limited to, a microprocessor, a microcontroller, a complex instruction set computing (CISC) microprocessor, a reduced instruction set (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, or any other type of processor or processing circuit.

In one embodiment, network interface 326 could be a wired interface such as a wireless interface would be a general packet radio service (GPRS) interface, a WiMAX interface, a 3G interface, a WiFi interface, or the like. In other embodiments, the network interface may be an Ethernet interface (see, e.g., Institute of Electrical and Electronics Engineers/IEEE 802.3-2002) or a wireless interface such as an IEEE 802.11a, b or g-compliant interface (see, e.g., IEEE Standard for IT-Telecommunications and information exchange between systems LAN/MAN—Part II: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 4: Further Higher Data Rate Extension in the 2.4 GHz Band, 802.11G-2003). Bus structures 328 connect various components of system hardware 320. In one embodiment, bus structures 328 may be one or more of several types of bus structure(s) including a memory bus, a peripheral bus or external bus, and/or a local bus using any variety of available bus architectures including, but not limited to, 11-bit bus, Industrial Standard Architecture (ISA), Micro-Channel Architecture (MSA), Extended ISA (EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB), Peripheral Component Interconnect (PCI), Universal Serial Bus (USB), Advanced Graphics Port (AGP), Personal Computer Memory Card International Association bus (PCMCIA), and Small Computer Systems Interface (SCSI).

Memory 330 may include an operating system 340 for managing operations of electronic device 300. In one embodiment, operating system 340 includes a hardware interface module 354 that provides an interface to system hardware 320. In addition, operating system 340 may include a file system 350 that manages files used in the operation of electronic device 300 and a process control subsystem 352 that manages processes executing on electronic device 300.

Operating system 340 may include (or manage) one or more communication interfaces 344 that may operate in conjunction with system hardware 320 to transceive data packets and/or data streams from a remote source. Operating system 340 may further include a system call interface module 342 that provides an interface between the operating system 340 and one or more application modules resident in memory 330. Operating system 340 may be embodied as a UNIX operating system or any derivative thereof (e.g., Linux, Solaris, etc.) or as a Windows® brand operating system, or other operating systems.

In various embodiments, the electronic device 300 may be coupled to a computing device 308, e.g., a personal computer, a laptop computer, a personal digital assistant, a mobile telephone, an entertainment device, or another computing device. Electronic device 300 may also be coupled to one or more accompanying input/output devices including a display 302 having a screen 304, one or more speakers 306, a keyboard 310, one or more other I/O device(s) 312, and a mouse 314. The other I/O device(s) 312 may include a touch screen, a voice-activated input device, a track ball, and any other device that allows the computing device 308 to receive input from a user.

A file store 380 may be communicatively coupled to one or more of the electronic device 300 or computing device 308. File store 380 may be an internal device such as, e.g., one or more hard drives, CD-ROM drives, DVD-ROM drives, or other types of storage devices. File store 380 may also be external to computer 308 such as, e.g., one or more external hard drives, network attached storage, or a separate storage network.

Referring back to FIG. 2, in brief overview the S101 interface between the MME 212 and the WiMAX BS 116 allows for preregistration and handover signaling to be exchanged in the context of a handover between networks. In some embodiments a layer 2 tunnel may be established between a UE/MS 110 and the WiMAX base station 116 and an S101 signaling interface may be implemented through the layer 2 tunnel between the MME 212 and the WiMAX base station 116. MIH is an example of layer-2 tunnel, while other tunneling functions may be possible. Preregistration operations and handover operations may be implemented at least in part via the layer 2 tunnel. In addition, an S103 signaling interface may be implemented between the ASN-GW 218 and the serving gateway 216. The S103 interface may be used to forward download data.

FIG. 4 is a flow diagram illustrating operations in a method to preregister a mobile station with a WiMAX network, according to embodiments. Referring to FIG. 4, in some embodiments the UE/MS may be registered in the MME 212 or in an ongoing data session with the 3GPP network. At operation 410 a decision is made to preregister the UE/MS 110 with a WiMAX. By way of example a user of the UE/MS may decide to preregister the UE/MS 110 with a WiMAX network. Alternatively, logic in the UE/MS 110 may decide to couple the UE/MS 110 to the WiMAX network.

At operation 412 a WiMAX SBC Req/Resp process is implemented between the UE/MS 110 and the WiMAX ASN-GW 212. At operation 414 Upload/Download information is transferred from the UE/MS 110 to the E-UTRAN 210. At operation 416 an S1 tunnel is implemented, and at operation 418 an S101 signaling interface is implemented between the MME 212 and the WiMAX BS 116 to enable WiMAX signaling to be transmitted directly over the S1 tunnel.

At operation 420 an R6 MS pre-attachment procedure is implemented between the WiMAX BS 116 and the WiMAX ASN-GW 212. At operation 422 a WiMAX Extensible Authentication Protocol Authentication and Key Agreement (EAP-AKA) authentication procedure is implemented to authenticate the UE/MS with the WiMAX network. At operation 424 a WiMAX Reg request/response process is implemented between the UE/MS 110 and the WMAX BS 116, and at operation 426 an MS Attachment req message is transmitted from the WiMAX BS 116 to the WiMAX ASN-GW 212 via the R6 interface. At operation 430 a WiMAX DSA Req/Rsp process is implemented between the UE/MS 110 and the WiMAX BS 110, and at operation 432 a Data Path Establishment message is transmitted between the WiMAX BS 116 and the WiMAX ASN-GW 212 via the R6 interface.

In some embodiments the UE/MS 110 is placed into an idle mode with the WiMAX access network after the UE/MS is preregistered with the WiMAX access network. Thus, at operation 434 a DREG Req operation is implemented between the UE/MS 110 and the WiMAX BS 116. In response to the request, an IM Entry State Change procedure 436 is implemented between the WiMAX BS 116 and the WiMAX ASN-GW 212 via the R6 interface. At operation 438 a data path deregistration operation is implemented between the WiMAX BS 116 and the WiMAX ASN-GW 212 via the R6 interface.

Thus, the operations of FIG. 4 enable preregistration of the UE/MS 110 with the WiMAX access network. In some embodiments signaling messages between UE/MS 110 and the WiMAX BS 116 take place, at least in part, via the S101 interface in the layer 2 tunnel established between the UE/MS 110 and the WiMAX BS 116. Further, in some embodiments the layer 2 tunnel is maintained after the UE/MS 110 is preregistred with the WiMAX access network. In addition, context information associated with the UE/MS 110 may be maintained after the mobile station has preregistered with the WiMAX ASN-GW 212.

FIG. 5 is a flow diagram illustrating operations in a method to implement a handover from a 3GPP access network, e.g., 3GPP access network, to a WiMAX access network, according to some embodiments. Referring to FIG. 5, the procedure starts with the UE/MS 110 connected to the E-UTRAN 210. At operation 510 one or more WiMAX power measurements collected by the UE/MS 110 are forwarded to the E-UTRAN 210. At operation 512 a decision is made to perform a handover from the 3GPP access network to the WiMAX access network. The handover decision may be made by the UE/MS 110, by the 3GPP network or another network element. In response to the handover decision, the E-UTRAN 210 transmits a handover command to the UE/MS 110 (operation 514). At operation 516 the WiMAX radio in the UE/MS 110 is switched on. At operation 518 the UE/MS 110 initiates a ranging request (RNG REQ) to a base station 116. In response to the RNG REQ the base station 116. At operation 520 the WiMAX BS 116 transmits an IM Exit State Change Req message to the target ASN-GW 212. In response to the IM Exit State Change Req, the ASN-GW 212 with which the UE/MS 110 is preregistered responds with an IM Exit State Change Rsp message 522.

At operation 524 the WiMAX BS 116 transmits a Path Reg Req message to the WiMAX ASN-GW 212. In response to the message, the WiMAX ASN-GW 212 generates a registration request/proxy binging update (RRQ/PBU) message 526 which is transmitted to the home agent/local management area, which responds with a RRP/PBA response 528. In response, the WiMAX ASN-GW 212 transmits a Path Reg Rsp message 530 to the WiMAX BS 116, which in turn issues a RNG-RSP message 532 to the UE/MS 110.

At operation 534 CMAC counter update procedure is implemented between the WiMAX BS 116 and the WiMAX ASN-GW 212. At operation 536 the WiMAX BS 116 transmits a Path Reg Ack message to the WiMAX ASN-GW 212, and at operation 538 the WiMAX ASN-GW transmits a Notification Request to the WiMAX BS 116 indicating that the handover is complete, and which the WiMAX BS 116 replies with a Notification Response 540.

At operation 542 the context information associated with the UE/MS 110 is released. At operation 544 the MME 212 transmits a Delete Bearer Request 544 to the serving gateway 216, which replies with a Delete Bearer response 546. Finally, at operation 548 the PDN-GW 222 initiates a resource deactivation procedure 548 at the E-UTRAN 210 to release the resources associated with the 3GPP access network.

FIG. 6 is a flow diagram illustrating operations in a method to implement a handover from a WiMAX access network to a 3GPP access network, according to some embodiments. The method begins with the WiMAX radio in the UE/MS 110 on. At operation 610 a decision is made to handover the UE/MS to the E-UTRAN 210 such that network access is provided by the 3GPP access network. In some embodiments the this decision may be made by the EU/MS 110, one or more components of the WiMAX access network, or both.

At operation 612 a MOB_MIH_MSG is transmitted from the UE/MS 110 to the WiMAX BS 116 which includes an Attach Request. In response to the MOB_MIH_MSG, the WiMAX BS 116 initiates a direct transfer via the layer 2 tunnel that includes the S101 session ID, the Attach Request, a descriptor of the capabilities of UE/MS 110, and TAI.

At operations 616-620 the UE/MS 110 may be authenticated with the 3GPP network. In some embodiments the UE/MS 110 transmits a MOB-MIH_MSG with an authentication attachment. In response to the MOB-MIH_MSG, the WiMAX BS 116 initiates a direct transfer via the layer 2 tunnel that includes the S101 session ID and the authentication request. At operation 620 an authentication process is implemented. In some embodiments the UE/MS may be authentication using an Authentication and Key Agreement (AKA) method, although other techniques may be used.

At operation 622 a location update and subscriber data retrieval process is implemented at the MME 212, and at operation 624 the MME passes a Create Session Request 624 to the serving gateway 216. At operation 626 the serving gateway 216 forwards the Create Session Request to the PDN-GW 222. In response to the request, the a PCEF initiated IP CAN-Session modification procedure 162 is implemented between the PDN-GW 222 an the PCRF 224. The PDN-GW 222 then sends a Create Session Response and a Bearer Request 632 to the serving gateway 216, which, at operation 634, forwards the request to the MME 212.

At operation 636 the MME 212 performs a direct transfer through the layer 2 tunnel which includes the S101 session ID, an Attach Accept and the Bearer Setup Request. At operation 638 the WiMAX BS 116 forwards the Attach Accept and the Bearer Setup Request to the UE/MS 110 via a MOB-MIH_MSG. At operation 640 the responds via a MOB-MIH_MSG with an Attach Complete and Bearer Setup Response. At operation 642 the WiMAX BS 116 forwards the Attach Complete message and Bearer Setup Response to the MME via a direct transfer through the layer 2 tunnel, and at operation 644 the MME forwards the Create Bearer Response to the serving gateway 216. At operation 646 the serving gateway 216 forwards the Create Bearer Response to the PDN-GW 222.

At operation 648 the LTE radio on the UE/MS 110 is turned on, and at operation 650 the UE/MS transmits an RRC connection request/service request message to the MME via the WiMAX BS 116. At operation 652 the MME 212 transmits an Initial UE Context setup Request to the eNB 240, which establishes an RRC RB with the UE/MS 110. At operation 656 the eNB transmits an Initial UE Context Setup Complete message to the MME 212. In response, the MME 212 transmits a Modify Bearer request 658 to the serving gateway 216, which provides a response at operation 660.

At operation 662 the MME 212 sends a Handover Complete message 662 to the WiMAX BS 116. In response to the message, WiMAX resources for the UE/MS 110 are released (operation 664) and the WiMAX ASN-GW initiates a resource allocation deactivation procedure to release WiMAX resources for the UE/MS 110.

Thus, the network architecture of FIG. 2 coupled with the operations depicted in FIGS. 4-6 enables single radio handover between a WiMAX access network and a 3GPP access network, e.g., a 3GPP network, using a layer 2 tunnel to transmit signaling information via a S101 signaling interface.

Various aspects of the radio access network parameters may be modified to accommodate a layer 2 capable handover. FIG. 7 is a schematic illustration of a state machine for a 3GPP LTE mobile station, according to embodiments. In some embodiments the 3GPP LTE state machine model may be adapted to change between an E-UTRA RRC Connected state and a WiMAX Active state on handover, and between an E-UTRA RRC Idle state and a WiMAX Idle state on reselection. Similarly, the state machine may be adapted to change between a WiMAX Active state and a WiMAX Idle state.

In some embodiments additional capabilities parameters may be included in the messaging between the UE/MS and the access network. In some embodiments WiMAX parameters are inserted into the UECapabilityInformation data structure as illustrated in FIG. 8 such that the network/eNB may be made aware that UE is capable of perform L2 handover into WiMAX network.

In some embodiments it may be desirable to allow a neighboring WiMAX base station to broadcast so that a mobile station does not have to perform blind scanning, which wastes battery power. In some embodiments, a new SIB (SystemInformationBlockTypeWiMAX) for broadcast WiMAX mobility related info may be introduced. Two aspects are needed for proper measurement operations: First, a neighbor list and configurations which informs about existing of other network. Second, a measurement triggers/threshold which this manages mobile station measurement behavior in a network controlled fashion. One example of a SIB is illustrated in FIG. 9.

In some embodiments aspects of the radio resource control (RRC) procedure may be modified to accommodate single radio handover from a 3GPP network to a WiMAX network. Define WiMAX in measurement configurations so that UE can obtain gap-base measurement interval to look for nearby WiMAX network. Table I presents a list of items which may be defined, with possible values listed below the items:

TABLE I RRC Procedures Measurement objects: a list of WiMAX neighbour BS Carrier frequency Preamble index Reporting configurations Quantity configurations: measurement metrics and filtering RSSI CINR others Measurement gaps: needed for single-radio UE 5 ms WiMAX frame granularity and interleaving pattern

A measurement report may be triggered based on network-defined triggers or thresholds specific to WiMAX. Once a measurement report is delivered to eNB, it enables eNB to make a handover decision based on the report.

One embodiment of an RRC procedure is shown in FIG. 10. Referring to FIG. 10, three signaling messages are passed between the UE/MS 110 and the E-UTRAN 210. At operation 1010 a ULHandoverPreparationRequest message is transmitted from the UE/MS 110 to the E-UTRAN. This is an optional signaling message which allows MS to initiate a handover request (WiMAX profile). It is an optional feature as WiMAX also supports fully BS controlled handover.

At operation 1015 a HandoverFromEUTRAPreparationRequest message is transmitted form the E-UTRAN 210 to the UE/MS 110. This is an optional signaling message which can be either in response of ULHandoverPreparationRequest or sent from eNB in an unsolicited fashion. This message allows MAC context pre-update from WiMAX TB, which is recommended for reducing interruption time. At operation 1020 a MobilityfromEUTRANcommand 1020 is transmitted from the UE/MS 110 to the E-UTRAN 201. This is a command for handover execution.

While particular terminology is used herein to describe various components and methods, one skilled in the art will recognize that such terminology is intended to be descriptive and not limiting. By way of example, the term base station is intended to refer to a device which provides access to a network, and the term femto access point is intended to refer to a device which provides access to a lower-level network within the network serviced by the base station. Similarly, the phrase “wireless device” is intended to refer to any type of device which can transmit or receive data on the network. It will be understood that these phrases are intended to apply to multiple different wireless networking standards and to networking standards and configurations not yet described or implemented.

The terms “logic instructions” as referred to herein relates to expressions which may be understood by one or more machines for performing one or more logical operations. For example, logic instructions may comprise instructions which are interpretable by a processor compiler for executing one or more operations on one or more data objects. However, this is merely an example of machine-readable instructions and embodiments are not limited in this respect.

The terms “computer readable medium” as referred to herein relates to media capable of maintaining expressions which are perceivable by one or more machines. For example, a computer readable medium may comprise one or more storage devices for storing computer readable instructions or data. Such storage devices may comprise storage media such as, for example, optical, magnetic or semiconductor storage media. However, this is merely an example of a computer readable medium and embodiments are not limited in this respect.

The term “logic” as referred to herein relates to structure for performing one or more logical operations. For example, logic may comprise circuitry which provides one or more output signals based upon one or more input signals. Such circuitry may comprise a finite state machine which receives a digital input and provides a digital output, or circuitry which provides one or more analog output signals in response to one or more analog input signals. Such circuitry may be provided in an application specific integrated circuit (ASIC) or field programmable gate array (FPGA). Also, logic may comprise machine-readable instructions stored in a memory in combination with processing circuitry to execute such machine-readable instructions. However, these are merely examples of structures which may provide logic and embodiments are not limited in this respect.

Some of the methods described herein may be embodied as logic instructions on a computer-readable medium. When executed on a processor, the logic instructions cause a processor to be programmed as a special-purpose machine that implements the described methods. The processor, when configured by the logic instructions to execute the methods described herein, constitutes structure for performing the described methods. Alternatively, the methods described herein may be reduced to logic on, e.g., a field programmable gate array (FPGA), an application specific integrated circuit (ASIC) or the like.

In the description and claims, the terms coupled and connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical or electrical contact with each other. Coupled may mean that two or more elements are in direct physical or electrical contact. However, coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate or interact with each other.

Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification may or may not be all referring to the same embodiment.

Although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that claimed subject matter may not be limited to the specific features or acts described. Rather, the specific features and acts are disclosed as sample forms of implementing the claimed subject matter. 

What is claimed is:
 1. A method, comprising: establishing a layer 2 tunnel between a mobile station coupled to a E-UTRAN and a WiMAX base station; implementing a first signaling interface through the layer 2 tunnel between a mobility management entity (MME) and the WiMAX base station; and preregistering the mobile station with the WiMAX access service network gateway at least in part via the layer 2 tunnel.
 2. The method of claim 1, further comprising maintaining the layer 2 tunnel after the mobile station is preregistered with the WiMAX access service network gateway.
 3. The method of claim 1, further comprising implementing a second signaling interface between a serving gateway and the WiMAX access service network gateway.
 4. The method of claim 3, wherein: the first signaling interface is an S101 signaling interface; and the second signaling interface is an S103 signaling interface.
 5. The method of claim 1, wherein preregistering a mobile station with the WiMAX access service network gateway at least in part via the layer 2 tunnel comprises at least one of: negotiating one or more capabilities of the mobile station; authenticating the mobile station; and establishing a data path for communication between the mobile station and the WiMAX base station.
 6. The method of claim 5, further comprising maintaining context information for the mobile station after the mobile station has preregistered with the WiMAX access service network gateway.
 7. The method of claim 1, further comprising: receiving a handover request from the mobile station via the layer 2 tunnel to allocate resources in a WiMAX access network for the mobile station; and in response to the request: allocating resources in the WiMAX access network; and coupling the mobile station to the WiMAX base station.
 8. The method of claim 7, further comprising maintaining the layer 2 tunnel after the mobile station is coupled to the WiMAX base station.
 9. The method of claim 7, further comprising releasing resources associated with the 3GPP access network after the mobile station is coupled to the WiMAX base station.
 10. The method of claim 9, further comprising updating a state machine for the mobile station when the mobile station is coupled to the WiMAX base station.
 11. The method of claim 8, further comprising: receiving a handover request from the mobile station via the layer 2 tunnel to implement a handover from the WiMAX network to the 3GPP network; and in response to the request: coupling the mobile station to the 3GPP network; and releasing resources in the WiMAX network.
 12. The method of claim 10, further comprising updating a state machine for the mobile station when the mobile station is coupled to the 3GPP network.
 13. A method to manage interworking between a WiMAX network and a 3GPP network, comprising: establishing a layer 2 tunnel between a mobile station coupled to E-UTRAN and a WiMAX base station; transmitting signaling between the mobile station and the WiMAX base station through an S101 signaling interface in the layer 2 tunnel.
 14. The method of claim 13, wherein the layer 2 tunnel is established prior to implementing a preregistration process to preregister the mobile station with a WiMAX access service network gateway.
 15. The method of claim 14, further comprising transmitting signaling between the WiMAX access service network gateway and a serving gateway through an S103 signaling interface.
 16. The method of claim 13, further comprising preregistering the mobile station with the WiMAX access service network gateway at least in part via the layer 2 tunnel.
 17. The method of claim 16, further comprising: receiving a handover request from the mobile station via the layer 2 tunnel to allocate resources in a WiMAX access network for the mobile station; and in response to the request: allocating resources in the WiMAX access network; and coupling the mobile station to the WiMAX base station. 